Department of Microbiology, Immunology, and Cancer Biology, University of Virginiagrid.27755.32, Charlottesville, Virginia, USA.
Department of Chemistry, University of Virginiagrid.27755.32, Charlottesville, Virginia, USA.
J Bacteriol. 2022 Apr 19;204(4):e0003522. doi: 10.1128/jb.00035-22. Epub 2022 Mar 28.
Neisseria gonorrhoeae infection is characterized by local and abundant recruitment of neutrophils. Despite neutrophils' antimicrobial activities, viable N. gonorrhoeae is recovered from infected individuals, leading to the question of how N. gonorrhoeae survives neutrophil attack. One feature impacting N. gonorrhoeae-neutrophil interactions is the phase-variable opacity-associated (Opa) proteins. Most Opa proteins engage human carcinoembryonic antigen-related cell adhesion molecules (CEACAMs) to facilitate bacterial binding and invasion. Neutrophils express two transmembrane CEACAMs, CEACAM1 and the granulocyte-specific CEACAM3. While N. gonorrhoeae isolated from infected individuals is frequently Opa, expression of OpaD from strain FA1090, which interacts with CEACAMs 1 and 3, is associated with reduced N. gonorrhoeae survival after exposure to human neutrophils. In this study, we hypothesized that the receptor-binding capability of individual Opa proteins impacts bacterial survival in the presence of neutrophils. To test this hypothesis, we introduced genes that are constitutively expressed into a derivative of strain FA1090 with all 11 genes deleted. The engineered genes encode Opa proteins that bind CEACAM1 and -3, CEACAM1 but not CEACAM3, or neither CEACAM1 nor -3. N. gonorrhoeae expressing CEACAM3-binding Opa proteins survived significantly less well than bacteria expressing other Opa proteins when exposed to primary human neutrophils. The CEACAM3-binding N. gonorrhoeae had significantly greater association with and internalization by neutrophils. However, once internalized, bacteria were similarly killed inside neutrophils, regardless of Opa expression. Furthermore, Opa expression did not significantly impact neutrophil granule mobilization. Our findings indicate that the extent to which Opa proteins mediate nonopsonic binding is the predominant determinant of bacterial survival from neutrophils. Neisseria gonorrhoeae, the cause of gonorrhea, is an urgent-threat pathogen due to increasing numbers of infections and increased antibiotic resistance. Many surface components of N. gonorrhoeae are phase variable, including the Opa protein family of adhesins and invasins. While Opa protein expression is selected for , bacteria expressing some Opa proteins are readily killed by neutrophils, which are recruited to sites of infection. The reason for this discrepancy has remained unresolved. Our work shows that Opa-dependent differences in bacterial survival after exposure to primary human neutrophils correlates with Opa-dependent bacterial binding and phagocytosis. These findings underscore how the ability of N. gonorrhoeae to change Opa expression through phase variation contributes to bacterial resistance to neutrophil clearance.
淋病奈瑟菌感染的特征是局部和大量中性粒细胞的募集。尽管中性粒细胞具有抗菌活性，但仍可从感染个体中回收存活的淋病奈瑟菌，这引发了一个问题，即淋病奈瑟菌如何在中性粒细胞攻击下存活。影响淋病奈瑟菌-中性粒细胞相互作用的一个特征是相变异构性不透明度相关（Opa）蛋白。大多数 Opa 蛋白与人类癌胚抗原相关细胞粘附分子（CEACAMs）结合，以促进细菌结合和入侵。中性粒细胞表达两种跨膜 CEACAMs，即 CEACAM1 和粒细胞特异性 CEACAM3。虽然从感染个体中分离的淋病奈瑟菌通常是 Opa，但来自菌株 FA1090 的 OpaD 的表达，其与 CEACAMs 1 和 3 相互作用，与暴露于人中性粒细胞后淋病奈瑟菌存活减少有关。在这项研究中，我们假设单个 Opa 蛋白的受体结合能力会影响细菌在存在中性粒细胞时的存活。为了验证这一假设，我们将基因引入到一个衍生菌株 FA1090 中，该菌株缺失了所有 11 个基因。工程基因编码与 CEACAM1 和 -3、CEACAM1 但不与 CEACAM3 结合或不与 CEACAM1 或 -3 结合的 Opa 蛋白。当暴露于原代人中性粒细胞时，表达与 CEACAM3 结合的 Opa 蛋白的淋病奈瑟菌的存活能力明显低于表达其他 Opa 蛋白的细菌。与中性粒细胞结合和内化的 CEACAM3 结合淋病奈瑟菌的数量明显更多。然而，一旦被内化，细菌在中性粒细胞内的杀灭情况相似，而与 Opa 的表达无关。此外，Opa 的表达并没有显著影响中性粒细胞颗粒的动员。我们的研究结果表明，Opa 蛋白介导非调理素结合的程度是决定淋病奈瑟菌从中性粒细胞中存活下来的主要决定因素。淋病奈瑟菌是淋病的病原体，由于感染人数增加和抗生素耐药性增加，它是一种紧急威胁病原体。淋病奈瑟菌的许多表面成分都是相变异构的，包括 Opa 蛋白家族的粘附素和入侵素。虽然 Opa 蛋白的表达是被选择的，但表达某些 Opa 蛋白的细菌很容易被中性粒细胞杀死，中性粒细胞被招募到感染部位。造成这种差异的原因仍未得到解决。我们的工作表明，暴露于原代人中性粒细胞后，Opa 依赖性细菌存活的差异与 Opa 依赖性细菌结合和吞噬作用相关。这些发现强调了淋病奈瑟菌通过相变异构改变 Opa 表达的能力如何有助于细菌抵抗中性粒细胞的清除。
